Switched mode electric power supplies must respond notably to various integration constraints, which include volume, weight or heat dissipation constraints. One solution allowing the volume and the weight of a switched mode electric power supply to be reduced is to decrease the area occupied by the magnetic circuits, and notably the transformer, while increasing the working frequency of these magnetic circuits.
When the working frequency of the magnetic circuits becomes high, that is higher than one megahertz, switched mode electric power supplies must then use a control comprising components that withstand high frequencies. This implies the use of new types of components, such as, for example, new generation MOS transistors. The use of such components forces a rethink of the arrangement of the electric circuits and may have a noticeable impact on the cost of manufacture, production and industrialization.
Another solution allowing the working frequency of the magnetic circuits to be increased is to use voltage controlled components (MOS technology components, insulated gate bipolar transistor etc.) having a high gate capacity. However, this solution generates an increase in heat dissipation as a function of the working frequency of the magnetic circuits. As a result of this, the efficiency of such a solution is never better than 90%. This solution is unsuited for low power power supplies (that is, power supplies of several tens of watts).